OBJECTIVES: Budget impact analysis is the traditional approach of assessing the affordability of new interventions. While vaccination has been shown to be one of the most cost-effective means to improve health, budget requirements can be a barrier. This study aims at comparing an affordability indicator of a new vaccine in countries with similar Gross Domestic Product (GDP) per capita, but different healthcare financing mechanisms. METHODS: Based on National Health Accounts data, analyses of Total Health Expenditures (THE) and share of Public Health Expenditures (PHE) of various middle income countries were performed. Brazil and Turkey were selected for in-depth analysis as they had comparable GDPs and healthcare expenditures per capita. Healthcare access and financing data were also obtained from various government sources for a quantitative analysis. The budget requirements for a new vaccine costing $40 Purchasing Power Parity (PPP) per immunized child covering 80% of the birth cohort were calculated and expressed as a share of PHE. RESULTS: THE per capita doubled over 10 years in both countries since 2001, reaching $1,037 (PPP) for Brazil and $1,160 for Turkey in 2011. However, the share of PHE is vastly different; 46% in Brazil compared to 75% in Turkey. Implementing the new vaccine would require an additional budget of $97Million and $42Million. While large in absolute values they represent only 0.11% of the PHE in Brazil and 0.07% in Turkey. The higher affordability in Turkey can be explained by a different financing mechanism. CONCLUSIONS: While the implementation of a new vaccine in comparable countries in terms of wealth and THE per capita would require significant additional national spending in absolute terms, it represents only a small fraction of the PHE. The underlying healthcare financing mechanisms is an important factor affecting the affordability of a new vaccination program.